Cable shoes are in the broadest sense understood as connectors which have a connecting portion in the shape of a hollow cylinder or a barrel-shaped ferrule, and a contact portion ("tongue"). The contact portion, e.g. in the form of a fork or of an eye, has the purpose of establishing electrical contact with a co-operating connector means, e.g. a stationary clamping screw. "Tongue" is in the present description and in the enclosed patent claims understood as any contact portion of a connector or terminal (be it of cable-shoe-type, or of end-sleeve-type).
The ferrule defines a portion for mechanical connection with, i.e. attachment to, the uninsulated end of an electrical conductor in order to establish electrical contact therewith.
Both the ferrule portion, and the contact portion consist of metal. The inserted conductor end does not extend beyond the ferrule, i.e. it does not penetrate into the contact portion. The ferrule, covered with an insulating layer, is afixed to the conductor by crimping.
Another type of terminals are end-sleeves, i.e. connector elements in which the stripped end of an electrical conductor is inserted into the contact portion (sleeve portion) and is crimped therein. There are also end-sleeves known which are provided either with a non-insulated metallic ferrule, or with a ferrule consisting exclusively of insulating material. The purpose of the metallic ferrule is to be crimped onto the insulation of the respective conductor, so as to reinforce the mechanical attachment of the end-sleeve to the conductor.
"Aderend-type end-sleeves with a plastic collar" are well known types of end-sleeves where non-metallic, all-plastic extruded collar portions (e.g. of polypropylen), also called "insertion funnels", are attached to all-metallic contact or sleeve portions in lieu of ferrules.
When such an end-sleeve is to be mounted on the bare end of a conductor (generally a multi-wire conductor), the conductor is stripped along a length corresponding to the length of the contact portion, and is through the insertion funnel introduced into the contact portion as to be there, and only there, crimped to a desired, possibly non-circular, cross-sectional profile, e.g a trapezoidal one.
The plastic collar loosely surrounds the end part of the conductor's insulation without seizing it firmly, because, not being made of metal, it cannot be crimped. For the same reason occupies the plastic insertion collar more space than a metallic ferrule, so that conductors provided with such end-sleeves cannot be crammed together so tightly as some connecting strips, with which the end-sleeves shall co-operate, demand.
Cable shoes and end-sleeves, besides of being produced individually, are also produced in the above mentioned strips or bands ("strip or band material"), and are removed therefrom first when they, e.g. by roll crimping, are attached to a conductor.
Various methods of producing intermediates for connectors with insulated ferrules have been described, e.g. in the U.S. Pat. Nos. 2,786,191 to Broske and 2,845,606 to Fuller.
According to the first named patent, a strip of sheet metal connector blanks, interconnected by slugs, is laminated with sheet plastic which subsequently is stamped out to leave an extension beyond the metal which can be formed into an insulation supporting sleeve. The blanks are so close together that there is no sufficient spacing between two neighbouring blanks for the insulation to be there folded back to the reverse side of the blank. The other patent describes a blank where metal is folded around plastic, not plastic around metal.
Insulation layers on ferrules, as well as the above mentioned insertion funnels, can be made in selected colors (e.g. red, yellow, green) defining color codes indicating a recommended range of conductor cross-sections for which the respective connector or terminal is best suited (e.g. in accordance with proposed German Standard DIN 46228, part 4, concerning the above mentioned so called "Aderend" end-sleeves with extruded collars).